
McGuirl et al. [1]} used both \(M\)  and \(X^\ell \)  cells to identify broken stripes in the ABM [2]} because Volkening et al.'s model produces \(X^\ell \)  cells at low density; see Figure REF (d). This rationale applies in the reverse to the CA [3]}: \(X^\ell \)  cells appear at high density in interstripes, whereas \(M\)  cells are at comparatively low density, particularly in wide stripes; see Figures REF (h) and REF (g). By flagging patterns as broken stripes only when the number of persistent loops is less than our expected number of stripes for both \(M\)  and \(X^\ell \)  cells, we allow for local dips in density for some stripe cells, as long as another type of stripe cell remains at consistently high enough density. We choose to focus on xanthophores and melanophores throughout our stripe-quantification pipeline; in the future, it would also be interesting to include iridophores.
